Air conditioning apparatus

Abstract

An air conditioning apparatus comprises a switching valve for switching the flowing direction of a refrigerant discharged from a compressor to carry out either cooling operation, heating operation or defrosting operation; an outdoor heat exchanger for receiving the refrigerant supplied by the compressor through the switching valve to make the refrigerant heat exchange with air to be heat exchanged; an indoor heat exchanger for making the refrigerant heat exchange with a fluid to be heat exchanged; an oil separator which is arranged in a discharging side refrigerant pipe connecting the switching valve and the discharge port of the compressor to separate the refrigerant and a refrigerating machine oil which are discharged from the compressor; a first and second accumulators which are connected in series in an intake side refrigerant pipe connecting the switching valve and the intake port of the compressor; a first bypass passage for connecting the oil separator and the second accumulator through a solenoid valve; and a second bypass passage for connecting the oil separator and the intake port of the compressor through a metering device. As a result, the refrigeranting machine oil is returned to the compressor through the first bypass passage or the first and second bypass passages to prevent the compressor from failing due to shortage of the refrigeranting machine oil.

What is claimed is: 
     
       1. An air conditioning apparatus comprising: a switching valve for switching the flowing direction of a refrigerant discharged from a compressor to carry out either cooling operation, heating operation or defrosting operation;   an outdoor heat exchanger for receiving the refrigerant supplied by the compressor through the switching valve to make the refrigerant heat exchange with air to be heat exchanged;   an indoor heat exchanger for making the refrigerant heat exchange with a fluid to be heat exchanged;   an oil separator which is arranged in a discharging side refrigerant pipe connecting the switching valve and the discharge port of the compressor to separate the refrigerant and a refrigerating machine oil which are discharged from the compressor;   a first and second accumulators which are connected in series in an intake side refrigerant pipe connecting the switching valve and the intake port of the compressor;   a first bypass passage for connecting the oil separator and the second accumulator through a solenoid valve; and   a second bypass passage for connecting the oil separator and the intake port of the compressor through a metering device.   
     
     
       2. An air conditioning apparatus according to claim 1, wherein the first bypass passage is connected to the second accumulator through a connecting pipe connecting the first and second accumulators. 
     
     
       3. An air conditioning apparatus according to claim 1, wherein the second bypass passage is connected to the intake port of the compressor through the intake side refrigerant pipe connecting the second accumulator and the intake port of the compressor. 
     
     
       4. An air conditioning apparatus according to claim 2, wherein the second bypass passage is connected to the intake port of the compressor through the intake side refrigerant pipe connecting the second accumulator and the intake port of the compressor. 
     
     
       5. An air conditioning apparatus according to claim 1, wherein the second bypass passage is connected to the intake port of the compressor through the second accumulator, and the intake side refrigerant pipe connecting the second accumulator and the intake port of the compressor. 
     
     
       6. An air conditioning apparatus according to claim 2, wherein the second bypass passage is connected to the intake port of the compressor through the second accumulator, and the intake side refrigerant pipe connecting the second accumulator and the intake port of the compressor. 
     
     
       7. An air conditioning apparatus according to claim 1, wherein the second bypass passage is connected to the intake port of the compressor through the connecting pipe connecting the first and second accumulators, the second accumulator, and the intake side refrigerant pipe connecting the second accumulator and the intake port of the compressor. 
     
     
       8. An air conditioning apparatus according to claim 2, wherein the second bypass passage is connected to the intake port of the compressor through the connecting pipe connecting the first and second accumulators, the second accumulator, and the intake side refrigerant pipe connecting the second accumulator and the intake port of the compressor. 
     
     
       9. An air conditioning appararus according to claim 1, wherein the flow rate in the first bypass passage is set to be greater than that in the second bypass passage. 
     
     
       10. An air conditioning appararus according to claim 2, wherein the flow rate in the first bypass passage is set to be greater than that in the second bypass passage. 
     
     
       11. An air conditioning appararus according to claim 3, wherein the flow rate in the first bypass passage is set to be greater than that in the second bypass passage. 
     
     
       12. An air conditioning appararus according to claim 4, wherein the flow rate in the first bypass passage is set to be greater than that in the second bypass passage. 
     
     
       13. An air conditioning appararus according to claim 5, wherein the flow rate in the first bypass passage is set to be greater than that in the second bypass passage. 
     
     
       14. An air conditioning appararus according to claim 6, wherein the flow rate in the first bypass passage is set to be greater than that in the second bypass passage. 
     
     
       15. An air conditioning appararus according to claim 7, wherein the flow rate in the first bypass passage is set to be greater than that in the second bypass passage. 
     
     
       16. An air conditioning appararus according to claim 8, wherein the flow rate in the first bypass passage is set to be greater than that in the second bypass passage. 
     
     
       17. An air conditioning apparatus according to claim 1, wherein there is provided control means for opening the solenoid valve during a predetermined time after the compressor has started. 
     
     
       18. An air conditioning apparatus according to claim 17, wherein the control means is constructed to continuously open the solenoid valve in the first bypass passage during the defrosting operation.